Oil sands (also referred to as tar sands or bituminous sands) are a naturally occurring combination of clay, sand, water, and bitumen, which is a heavy black viscous oil. Oil sands can be mined and processed to extract bitumen, which is upgraded into synthetic crude oil or refined directly into petroleum products.
Most of the world's oil, in excess of 5 trillion barrels, is in the form of oil sands. The largest deposits of oil sands are found in Alberta, Canada and Venezuela. In the United States, oil sands resources are primarily concentrated in Eastern Utah. The oil sands resources in Utah are estimated at being in the range 12 to 20 billion barrels of oil.
The bitumen in oil sands typically cannot be pumped from the ground in its natural state. Oil sands deposits are mined or produced using in situ (“in place”) recovery methods. In one known surface mining method, oil sands deposits near the surface are recovered by open pit mining techniques, which use large hydraulic/electric powered shovels to remove oil sands and load trucks for transport to an extraction plant, which includes a hot water process that separates the bitumen from the sand, water and minerals. After the hot water is added to the oil sands, the resulting slurry is piped to the extraction plant where it is agitated, with for example a caustic agent such as NaOH, to release bitumen from the oil sand. The bitumen is transported for upgrading and/or refining, however, bitumen is much thicker than traditional crude oil so it can be mixed with lighter petroleum or chemically altered to facilitate transport.
Surface mining methods may also include other enhancements such as tailings oil recovery (TOR) that recovers oil from the tailings of the oil sands, diluent recovery units to recover naptha from the froth of the slurry, inclined plate settlers (IPS) and disc centrifuges. These surface attempts to extract hydrocarbon products from oil sands have been, however, costly, energy intensive and inefficient. Further, these methods can create negative environmental impacts due to the clearing of trees and other disruption of the top layer of earth to expose oil sands deposits. In addition, it has been established that approximately 80% of all oil sands deposits are too deep to be recovered using traditional surface mining methods.
Attempts have been made to overcome the drawbacks of prior known surface mining methods of recovery, and to extract subterranean oil sands deposits, by employing in situ processes. These techniques may include steam injection, solvent injection and firefloods, in which oxygen and/or air is injected and part of the resource burned to provide heat. In one in-situ technique, a cyclic steam stimulation method (CSS) is employed whereby a producing well is cycled through steam injection, soak and oil production. Steam is injected into the well at a temperature of approximately 300 degrees Celsius for a period of weeks to months. The well sits for days to weeks such that heat soaks into the formation. Then, hot oil is pumped out of the well for a period of weeks or months. As the production rate falls, the well is cycled through another procedure of injection, soak and production. The process is repeated until the cost of injecting steam outweighs the value of the produced oil.
In another in-situ technique, a steam assisted gravity drainage method (SAGD) is used that employs directional drilling whereby two horizontal wells are drilled in the oil sands, a lower well at the bottom of the formation and an upper well above it. In each well pair, steam is injected into the upper well to heat the bitumen, lowering the viscosity such that the bitumen flows into the lower well and is pumped to the surface. In a similar technique, a vapor extraction process (VAPEX) uses hydrocarbon solvents, alternative to steam or mixed with steam, which are injected into the upper well to dilute the bitumen, which flows into the lower well. In a fireflood technique, a toe to heel air injection method (THAI) employs a vertical air injection well with a horizontal production well whereby oil in the reservoir is ignited to create a vertical wall of fire moving from the “toe” of the horizontal well toward the “heel.” This process burns the heavier oil components and drives the lighter components into the production well to be pumped to the surface.
After bitumen is extracted, bitumen can be upgraded for processing in refineries. Upgrading includes removing carbon from the bitumen while adding hydrogen to produce a more valuable hydrocarbon product such as synthetic crude oil, which may be shipped to a refinery, by for example underground and above ground pipelines. The oil can be further refined into aviation fuels, gasoline, diesel fuel, and other petroleum products and petroleum chemical products such as plastics, fleece, toothpaste, etc.
These known in-situ methods of bitumen extraction, however, suffer from various drawbacks and disadvantages. For example, the above described techniques can be expensive, including high energy costs for the large amount of energy required, require large amounts of water, as well as negative environmental impacts. These impacts may include global warming, greenhouse gas emissions and disturbance of land, as well as impacts on wildlife, air and water quality.
Oil sands production as currently practiced releases significant quantities of carbon dioxide, which is a contributor to GHG emissions linked to global warming. A large contributor to GHG emissions growth in Canada is oil sands production. Aggressive growth in oil sands recovery signals a need for focus on reducing GHGs. Annual emission from the oil sands production are projected to grow from approximately 40 megatons to over 100 megatons by 2015. Further, there are large reservoirs of waste water from oil sands extraction processes that cannot be released into the surface water supply or reinjected underground because of contaminants.
These known surface mining and in-situ methods also require significant inputs of energy. The upgraders and refineries, which extract hydrocarbons from oil sands and bitumen, are fueled by finished hydrocarbons resulting in substantial atmospheric pollution and use of non-renewable resources. Also, there is an environmental tradeoff characterized by combusting more finished hydrocarbons such as natural gas, to remediate waste water and other waste streams from the existing processes being used.
Therefore, it would be desirable to overcome the disadvantages and drawbacks of the prior art with a method and system for recovering hydrocarbon products from formations, such as oil sands, which heat the oil sands via thermal and/or electrically induced energy produced by a nuclear reactor. Further, the ancillary and auxiliary uses of energy including, but not limited to feed water treatment, waste water treatment, produced water treatment, bitumen upgrading, synthetic crude oil (SCO) refining, hydrogen production, electric energy production, disposal methods, petrochemical production, fracturing of oil sands deposits, enhancing gasification (including thermal energy and air separation) and greenhouse gases sequestration, among others, can be accomplished using nuclear energy sources. It is most desirable that the method and system of the present invention is advantageously employed to minimize energy input costs, limit water use and reduce the emission of greenhouse gases and other emissions and effluents, such as carbon dioxide and other gases and liquids, and to minimize environmental impacts from oil sands oil production.